As railroad cars are loaded with a cargo, such as a liquid or solid material, they must be weighed before, during and after loading, so that a preselected amount of material can be added to each car, and to prevent overloading of the cars. The standard practice for doing this is to pull the railroad car to be weighed along a set of railroad tracks until the rail car overlies and is centered over a fixed scale mounted on the tracks. In order to give a true weight that is not influenced by pulling or pushing from adjacent cars, the car to be weighed is uncoupled from each of its adjacent cars while it is over the scale during the weighing process. When loading has been completed, the car must be re-coupled to its adjacent cars prior to moving the loaded car forward and moving the next car into position over the scale. This coupling and uncoupling adds a great deal of time and adds substantial expense to the weighing and loading of the car.
When large scale shippers, such as shippers of grain, coal and other industrial products, must weigh a large number of rail cars, the time required for uncoupling, weighing and re-coupling each rail car one at a time is very costly. Thus an alternate method has been proposed, whereby a rail car is moved across a stationary scale while remaining coupled to adjoining cars. However, in order to maintain accuracy and preclude the adjacent cars from influencing the weight of the rail car being weighed, the rail track must be absolutely level for the whole length of all of the coupled cars in order to effect this means in the prior art. Thus generally a parallel set of level tracks must be separately built alongside the main rail track line, for the length of the train, together with tracks connecting the parallel set of tracks to the main tracks at each end. This is an expensive solution, both in terms of building the level parallel tracks and in providing the space requirements for them.
Thus the present Hobson's choice of the known prior art is either to take the time to de-couple and re-couple each rail car during weighing and loading, which is very expensive in the long run, or to build a level set of parallel tracks and a new weighing facility, which may cost millions of dollars in up front costs.
Accordingly, a substantially novel and innovative method for weighing rail cars prior to and after being loaded, while avoiding some or all of the above time consumption and expense, would be highly desirable.